Java example source code file (memTracker.cpp)
The memTracker.cpp Java example source code
/*
* Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "oops/instanceKlass.hpp"
#include "runtime/atomic.hpp"
#include "runtime/interfaceSupport.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/safepoint.hpp"
#include "runtime/threadCritical.hpp"
#include "runtime/vm_operations.hpp"
#include "services/memPtr.hpp"
#include "services/memReporter.hpp"
#include "services/memTracker.hpp"
#include "utilities/decoder.hpp"
#include "utilities/defaultStream.hpp"
#include "utilities/globalDefinitions.hpp"
bool NMT_track_callsite = false;
// walk all 'known' threads at NMT sync point, and collect their recorders
void SyncThreadRecorderClosure::do_thread(Thread* thread) {
assert(SafepointSynchronize::is_at_safepoint(), "Safepoint required");
if (thread->is_Java_thread()) {
JavaThread* javaThread = (JavaThread*)thread;
MemRecorder* recorder = javaThread->get_recorder();
if (recorder != NULL) {
MemTracker::enqueue_pending_recorder(recorder);
javaThread->set_recorder(NULL);
}
}
_thread_count ++;
}
MemRecorder* volatile MemTracker::_global_recorder = NULL;
MemSnapshot* MemTracker::_snapshot = NULL;
MemBaseline MemTracker::_baseline;
Mutex* MemTracker::_query_lock = NULL;
MemRecorder* volatile MemTracker::_merge_pending_queue = NULL;
MemRecorder* volatile MemTracker::_pooled_recorders = NULL;
MemTrackWorker* MemTracker::_worker_thread = NULL;
int MemTracker::_sync_point_skip_count = 0;
MemTracker::NMTLevel MemTracker::_tracking_level = MemTracker::NMT_off;
volatile MemTracker::NMTStates MemTracker::_state = NMT_uninited;
MemTracker::ShutdownReason MemTracker::_reason = NMT_shutdown_none;
int MemTracker::_thread_count = 255;
volatile jint MemTracker::_pooled_recorder_count = 0;
volatile unsigned long MemTracker::_processing_generation = 0;
volatile bool MemTracker::_worker_thread_idle = false;
volatile jint MemTracker::_pending_op_count = 0;
volatile bool MemTracker::_slowdown_calling_thread = false;
debug_only(intx MemTracker::_main_thread_tid = 0;)
NOT_PRODUCT(volatile jint MemTracker::_pending_recorder_count = 0;)
void MemTracker::init_tracking_options(const char* option_line) {
_tracking_level = NMT_off;
if (strcmp(option_line, "=summary") == 0) {
_tracking_level = NMT_summary;
} else if (strcmp(option_line, "=detail") == 0) {
// detail relies on a stack-walking ability that may not
// be available depending on platform and/or compiler flags
#if PLATFORM_NATIVE_STACK_WALKING_SUPPORTED
_tracking_level = NMT_detail;
#else
jio_fprintf(defaultStream::error_stream(),
"NMT detail is not supported on this platform. Using NMT summary instead.\n");
_tracking_level = NMT_summary;
#endif
} else if (strcmp(option_line, "=off") != 0) {
vm_exit_during_initialization("Syntax error, expecting -XX:NativeMemoryTracking=[off|summary|detail]", NULL);
}
}
// first phase of bootstrapping, when VM is still in single-threaded mode.
void MemTracker::bootstrap_single_thread() {
if (_tracking_level > NMT_off) {
assert(_state == NMT_uninited, "wrong state");
// NMT is not supported with UseMallocOnly is on. NMT can NOT
// handle the amount of malloc data without significantly impacting
// runtime performance when this flag is on.
if (UseMallocOnly) {
shutdown(NMT_use_malloc_only);
return;
}
_query_lock = new (std::nothrow) Mutex(Monitor::max_nonleaf, "NMT_queryLock");
if (_query_lock == NULL) {
shutdown(NMT_out_of_memory);
return;
}
debug_only(_main_thread_tid = os::current_thread_id();)
_state = NMT_bootstrapping_single_thread;
NMT_track_callsite = (_tracking_level == NMT_detail && can_walk_stack());
}
}
// second phase of bootstrapping, when VM is about to or already entered multi-theaded mode.
void MemTracker::bootstrap_multi_thread() {
if (_tracking_level > NMT_off && _state == NMT_bootstrapping_single_thread) {
// create nmt lock for multi-thread execution
assert(_main_thread_tid == os::current_thread_id(), "wrong thread");
_state = NMT_bootstrapping_multi_thread;
NMT_track_callsite = (_tracking_level == NMT_detail && can_walk_stack());
}
}
// fully start nmt
void MemTracker::start() {
// Native memory tracking is off from command line option
if (_tracking_level == NMT_off || shutdown_in_progress()) return;
assert(_main_thread_tid == os::current_thread_id(), "wrong thread");
assert(_state == NMT_bootstrapping_multi_thread, "wrong state");
_snapshot = new (std::nothrow)MemSnapshot();
if (_snapshot != NULL) {
if (!_snapshot->out_of_memory() && start_worker(_snapshot)) {
_state = NMT_started;
NMT_track_callsite = (_tracking_level == NMT_detail && can_walk_stack());
return;
}
delete _snapshot;
_snapshot = NULL;
}
// fail to start native memory tracking, shut it down
shutdown(NMT_initialization);
}
/**
* Shutting down native memory tracking.
* We can not shutdown native memory tracking immediately, so we just
* setup shutdown pending flag, every native memory tracking component
* should orderly shut itself down.
*
* The shutdown sequences:
* 1. MemTracker::shutdown() sets MemTracker to shutdown pending state
* 2. Worker thread calls MemTracker::final_shutdown(), which transites
* MemTracker to final shutdown state.
* 3. At sync point, MemTracker does final cleanup, before sets memory
* tracking level to off to complete shutdown.
*/
void MemTracker::shutdown(ShutdownReason reason) {
if (_tracking_level == NMT_off) return;
if (_state <= NMT_bootstrapping_single_thread) {
// we still in single thread mode, there is not contention
_state = NMT_shutdown_pending;
_reason = reason;
} else {
// we want to know who initialized shutdown
if ((jint)NMT_started == Atomic::cmpxchg((jint)NMT_shutdown_pending,
(jint*)&_state, (jint)NMT_started)) {
_reason = reason;
}
}
}
// final phase of shutdown
void MemTracker::final_shutdown() {
// delete all pending recorders and pooled recorders
delete_all_pending_recorders();
delete_all_pooled_recorders();
{
// shared baseline and snapshot are the only objects needed to
// create query results
MutexLockerEx locker(_query_lock, true);
// cleanup baseline data and snapshot
_baseline.clear();
delete _snapshot;
_snapshot = NULL;
}
// shutdown shared decoder instance, since it is only
// used by native memory tracking so far.
Decoder::shutdown();
MemTrackWorker* worker = NULL;
{
ThreadCritical tc;
// can not delete worker inside the thread critical
if (_worker_thread != NULL && Thread::current() == _worker_thread) {
worker = _worker_thread;
_worker_thread = NULL;
}
}
if (worker != NULL) {
delete worker;
}
_state = NMT_final_shutdown;
}
// delete all pooled recorders
void MemTracker::delete_all_pooled_recorders() {
// free all pooled recorders
MemRecorder* volatile cur_head = _pooled_recorders;
if (cur_head != NULL) {
MemRecorder* null_ptr = NULL;
while (cur_head != NULL && (void*)cur_head != Atomic::cmpxchg_ptr((void*)null_ptr,
(void*)&_pooled_recorders, (void*)cur_head)) {
cur_head = _pooled_recorders;
}
if (cur_head != NULL) {
delete cur_head;
_pooled_recorder_count = 0;
}
}
}
// delete all recorders in pending queue
void MemTracker::delete_all_pending_recorders() {
// free all pending recorders
MemRecorder* pending_head = get_pending_recorders();
if (pending_head != NULL) {
delete pending_head;
}
}
/*
* retrieve per-thread recorder of specified thread.
* if thread == NULL, it means global recorder
*/
MemRecorder* MemTracker::get_thread_recorder(JavaThread* thread) {
if (shutdown_in_progress()) return NULL;
MemRecorder* rc;
if (thread == NULL) {
rc = _global_recorder;
} else {
rc = thread->get_recorder();
}
if (rc != NULL && rc->is_full()) {
enqueue_pending_recorder(rc);
rc = NULL;
}
if (rc == NULL) {
rc = get_new_or_pooled_instance();
if (thread == NULL) {
_global_recorder = rc;
} else {
thread->set_recorder(rc);
}
}
return rc;
}
/*
* get a per-thread recorder from pool, or create a new one if
* there is not one available.
*/
MemRecorder* MemTracker::get_new_or_pooled_instance() {
MemRecorder* cur_head = const_cast<MemRecorder*> (_pooled_recorders);
if (cur_head == NULL) {
MemRecorder* rec = new (std::nothrow)MemRecorder();
if (rec == NULL || rec->out_of_memory()) {
shutdown(NMT_out_of_memory);
if (rec != NULL) {
delete rec;
rec = NULL;
}
}
return rec;
} else {
MemRecorder* next_head = cur_head->next();
if ((void*)cur_head != Atomic::cmpxchg_ptr((void*)next_head, (void*)&_pooled_recorders,
(void*)cur_head)) {
return get_new_or_pooled_instance();
}
cur_head->set_next(NULL);
Atomic::dec(&_pooled_recorder_count);
cur_head->set_generation();
return cur_head;
}
}
/*
* retrieve all recorders in pending queue, and empty the queue
*/
MemRecorder* MemTracker::get_pending_recorders() {
MemRecorder* cur_head = const_cast<MemRecorder*>(_merge_pending_queue);
MemRecorder* null_ptr = NULL;
while ((void*)cur_head != Atomic::cmpxchg_ptr((void*)null_ptr, (void*)&_merge_pending_queue,
(void*)cur_head)) {
cur_head = const_cast<MemRecorder*>(_merge_pending_queue);
}
NOT_PRODUCT(Atomic::store(0, &_pending_recorder_count));
return cur_head;
}
/*
* release a recorder to recorder pool.
*/
void MemTracker::release_thread_recorder(MemRecorder* rec) {
assert(rec != NULL, "null recorder");
// we don't want to pool too many recorders
rec->set_next(NULL);
if (shutdown_in_progress() || _pooled_recorder_count > _thread_count * 2) {
delete rec;
return;
}
rec->clear();
MemRecorder* cur_head = const_cast<MemRecorder*>(_pooled_recorders);
rec->set_next(cur_head);
while ((void*)cur_head != Atomic::cmpxchg_ptr((void*)rec, (void*)&_pooled_recorders,
(void*)cur_head)) {
cur_head = const_cast<MemRecorder*>(_pooled_recorders);
rec->set_next(cur_head);
}
Atomic::inc(&_pooled_recorder_count);
}
// write a record to proper recorder. No lock can be taken from this method
// down.
void MemTracker::write_tracking_record(address addr, MEMFLAGS flags,
size_t size, jint seq, address pc, JavaThread* thread) {
MemRecorder* rc = get_thread_recorder(thread);
if (rc != NULL) {
rc->record(addr, flags, size, seq, pc);
}
}
/**
* enqueue a recorder to pending queue
*/
void MemTracker::enqueue_pending_recorder(MemRecorder* rec) {
assert(rec != NULL, "null recorder");
// we are shutting down, so just delete it
if (shutdown_in_progress()) {
rec->set_next(NULL);
delete rec;
return;
}
MemRecorder* cur_head = const_cast<MemRecorder*>(_merge_pending_queue);
rec->set_next(cur_head);
while ((void*)cur_head != Atomic::cmpxchg_ptr((void*)rec, (void*)&_merge_pending_queue,
(void*)cur_head)) {
cur_head = const_cast<MemRecorder*>(_merge_pending_queue);
rec->set_next(cur_head);
}
NOT_PRODUCT(Atomic::inc(&_pending_recorder_count);)
}
/*
* The method is called at global safepoint
* during it synchronization process.
* 1. enqueue all JavaThreads' per-thread recorders
* 2. enqueue global recorder
* 3. retrieve all pending recorders
* 4. reset global sequence number generator
* 5. call worker's sync
*/
#define MAX_SAFEPOINTS_TO_SKIP 128
#define SAFE_SEQUENCE_THRESHOLD 30
#define HIGH_GENERATION_THRESHOLD 60
#define MAX_RECORDER_THREAD_RATIO 30
#define MAX_RECORDER_PER_THREAD 100
void MemTracker::sync() {
assert(_tracking_level > NMT_off, "NMT is not enabled");
assert(SafepointSynchronize::is_at_safepoint(), "Safepoint required");
// Some GC tests hit large number of safepoints in short period of time
// without meaningful activities. We should prevent going to
// sync point in these cases, which can potentially exhaust generation buffer.
// Here is the factots to determine if we should go into sync point:
// 1. not to overflow sequence number
// 2. if we are in danger to overflow generation buffer
// 3. how many safepoints we already skipped sync point
if (_state == NMT_started) {
// worker thread is not ready, no one can manage generation
// buffer, so skip this safepoint
if (_worker_thread == NULL) return;
if (_sync_point_skip_count < MAX_SAFEPOINTS_TO_SKIP) {
int per_seq_in_use = SequenceGenerator::peek() * 100 / max_jint;
int per_gen_in_use = _worker_thread->generations_in_use() * 100 / MAX_GENERATIONS;
if (per_seq_in_use < SAFE_SEQUENCE_THRESHOLD && per_gen_in_use >= HIGH_GENERATION_THRESHOLD) {
_sync_point_skip_count ++;
return;
}
}
{
// This method is running at safepoint, with ThreadCritical lock,
// it should guarantee that NMT is fully sync-ed.
ThreadCritical tc;
// We can NOT execute NMT sync-point if there are pending tracking ops.
if (_pending_op_count == 0) {
SequenceGenerator::reset();
_sync_point_skip_count = 0;
// walk all JavaThreads to collect recorders
SyncThreadRecorderClosure stc;
Threads::threads_do(&stc);
_thread_count = stc.get_thread_count();
MemRecorder* pending_recorders = get_pending_recorders();
if (_global_recorder != NULL) {
_global_recorder->set_next(pending_recorders);
pending_recorders = _global_recorder;
_global_recorder = NULL;
}
// see if NMT has too many outstanding recorder instances, it usually
// means that worker thread is lagging behind in processing them.
if (!AutoShutdownNMT) {
_slowdown_calling_thread = (MemRecorder::_instance_count > MAX_RECORDER_THREAD_RATIO * _thread_count);
} else {
// If auto shutdown is on, enforce MAX_RECORDER_PER_THREAD threshold to prevent OOM
if (MemRecorder::_instance_count >= _thread_count * MAX_RECORDER_PER_THREAD) {
shutdown(NMT_out_of_memory);
}
}
// check _worker_thread with lock to avoid racing condition
if (_worker_thread != NULL) {
_worker_thread->at_sync_point(pending_recorders, InstanceKlass::number_of_instance_classes());
}
assert(SequenceGenerator::peek() == 1, "Should not have memory activities during sync-point");
} else {
_sync_point_skip_count ++;
}
}
}
// now, it is the time to shut whole things off
if (_state == NMT_final_shutdown) {
// walk all JavaThreads to delete all recorders
SyncThreadRecorderClosure stc;
Threads::threads_do(&stc);
// delete global recorder
{
ThreadCritical tc;
if (_global_recorder != NULL) {
delete _global_recorder;
_global_recorder = NULL;
}
}
MemRecorder* pending_recorders = get_pending_recorders();
if (pending_recorders != NULL) {
delete pending_recorders;
}
// try at a later sync point to ensure MemRecorder instance drops to zero to
// completely shutdown NMT
if (MemRecorder::_instance_count == 0) {
_state = NMT_shutdown;
_tracking_level = NMT_off;
}
}
}
/*
* Start worker thread.
*/
bool MemTracker::start_worker(MemSnapshot* snapshot) {
assert(_worker_thread == NULL && _snapshot != NULL, "Just Check");
_worker_thread = new (std::nothrow) MemTrackWorker(snapshot);
if (_worker_thread == NULL) {
return false;
} else if (_worker_thread->has_error()) {
delete _worker_thread;
_worker_thread = NULL;
return false;
}
_worker_thread->start();
return true;
}
/*
* We need to collect a JavaThread's per-thread recorder
* before it exits.
*/
void MemTracker::thread_exiting(JavaThread* thread) {
if (is_on()) {
MemRecorder* rec = thread->get_recorder();
if (rec != NULL) {
enqueue_pending_recorder(rec);
thread->set_recorder(NULL);
}
}
}
// baseline current memory snapshot
bool MemTracker::baseline() {
MutexLocker lock(_query_lock);
MemSnapshot* snapshot = get_snapshot();
if (snapshot != NULL) {
return _baseline.baseline(*snapshot, false);
}
return false;
}
// print memory usage from current snapshot
bool MemTracker::print_memory_usage(BaselineOutputer& out, size_t unit, bool summary_only) {
MemBaseline baseline;
MutexLocker lock(_query_lock);
MemSnapshot* snapshot = get_snapshot();
if (snapshot != NULL && baseline.baseline(*snapshot, summary_only)) {
BaselineReporter reporter(out, unit);
reporter.report_baseline(baseline, summary_only);
return true;
}
return false;
}
// Whitebox API for blocking until the current generation of NMT data has been merged
bool MemTracker::wbtest_wait_for_data_merge() {
// NMT can't be shutdown while we're holding _query_lock
MutexLocker lock(_query_lock);
assert(_worker_thread != NULL, "Invalid query");
// the generation at query time, so NMT will spin till this generation is processed
unsigned long generation_at_query_time = SequenceGenerator::current_generation();
unsigned long current_processing_generation = _processing_generation;
// if generation counter overflown
bool generation_overflown = (generation_at_query_time < current_processing_generation);
long generations_to_wrap = MAX_UNSIGNED_LONG - current_processing_generation;
// spin
while (!shutdown_in_progress()) {
if (!generation_overflown) {
if (current_processing_generation > generation_at_query_time) {
return true;
}
} else {
assert(generations_to_wrap >= 0, "Sanity check");
long current_generations_to_wrap = MAX_UNSIGNED_LONG - current_processing_generation;
assert(current_generations_to_wrap >= 0, "Sanity check");
// to overflow an unsigned long should take long time, so to_wrap check should be sufficient
if (current_generations_to_wrap > generations_to_wrap &&
current_processing_generation > generation_at_query_time) {
return true;
}
}
// if worker thread is idle, but generation is not advancing, that means
// there is not safepoint to let NMT advance generation, force one.
if (_worker_thread_idle) {
VM_ForceSafepoint vfs;
VMThread::execute(&vfs);
}
MemSnapshot* snapshot = get_snapshot();
if (snapshot == NULL) {
return false;
}
snapshot->wait(1000);
current_processing_generation = _processing_generation;
}
// We end up here if NMT is shutting down before our data has been merged
return false;
}
// compare memory usage between current snapshot and baseline
bool MemTracker::compare_memory_usage(BaselineOutputer& out, size_t unit, bool summary_only) {
MutexLocker lock(_query_lock);
if (_baseline.baselined()) {
MemBaseline baseline;
MemSnapshot* snapshot = get_snapshot();
if (snapshot != NULL && baseline.baseline(*snapshot, summary_only)) {
BaselineReporter reporter(out, unit);
reporter.diff_baselines(baseline, _baseline, summary_only);
return true;
}
}
return false;
}
#ifndef PRODUCT
void MemTracker::walk_stack(int toSkip, char* buf, int len) {
int cur_len = 0;
char tmp[1024];
address pc;
while (cur_len < len) {
pc = os::get_caller_pc(toSkip + 1);
if (pc != NULL && os::dll_address_to_function_name(pc, tmp, sizeof(tmp), NULL)) {
jio_snprintf(&buf[cur_len], (len - cur_len), "%s\n", tmp);
cur_len = (int)strlen(buf);
} else {
buf[cur_len] = '\0';
break;
}
toSkip ++;
}
}
void MemTracker::print_tracker_stats(outputStream* st) {
st->print_cr("\nMemory Tracker Stats:");
st->print_cr("\tMax sequence number = %d", SequenceGenerator::max_seq_num());
st->print_cr("\tthead count = %d", _thread_count);
st->print_cr("\tArena instance = %d", Arena::_instance_count);
st->print_cr("\tpooled recorder count = %d", _pooled_recorder_count);
st->print_cr("\tqueued recorder count = %d", _pending_recorder_count);
st->print_cr("\tmemory recorder instance count = %d", MemRecorder::_instance_count);
if (_worker_thread != NULL) {
st->print_cr("\tWorker thread:");
st->print_cr("\t\tSync point count = %d", _worker_thread->_sync_point_count);
st->print_cr("\t\tpending recorder count = %d", _worker_thread->count_pending_recorders());
st->print_cr("\t\tmerge count = %d", _worker_thread->_merge_count);
} else {
st->print_cr("\tWorker thread is not started");
}
st->print_cr(" ");
if (_snapshot != NULL) {
_snapshot->print_snapshot_stats(st);
} else {
st->print_cr("No snapshot");
}
}
#endif
// Tracker Implementation
/*
* Create a tracker.
* This is a fairly complicated constructor, as it has to make two important decisions:
* 1) Does it need to take ThreadCritical lock to write tracking record
* 2) Does it need to pre-reserve a sequence number for the tracking record
*
* The rules to determine if ThreadCritical is needed:
* 1. When nmt is in single-threaded bootstrapping mode, no lock is needed as VM
* still in single thread mode.
* 2. For all threads other than JavaThread, ThreadCritical is needed
* to write to recorders to global recorder.
* 3. For JavaThreads that are no longer visible by safepoint, also
* need to take ThreadCritical and records are written to global
* recorders, since these threads are NOT walked by Threads.do_thread().
* 4. JavaThreads that are running in safepoint-safe states do not stop
* for safepoints, ThreadCritical lock should be taken to write
* memory records.
* 5. JavaThreads that are running in VM state do not need any lock and
* records are written to per-thread recorders.
* 6. For a thread has yet to attach VM 'Thread', they need to take
* ThreadCritical to write to global recorder.
*
* The memory operations that need pre-reserve sequence numbers:
* The memory operations that "release" memory blocks and the
* operations can fail, need to pre-reserve sequence number. They
* are realloc, uncommit and release.
*
* The reason for pre-reserve sequence number, is to prevent race condition:
* Thread 1 Thread 2
* <release>
* <allocate>
* <write allocate record>
* <write release record>
* if Thread 2 happens to obtain the memory address Thread 1 just released,
* then NMT can mistakenly report the memory is free.
*
* Noticeably, free() does not need pre-reserve sequence number, because the call
* does not fail, so we can alway write "release" record before the memory is actaully
* freed.
*
* For realloc, uncommit and release, following coding pattern should be used:
*
* MemTracker::Tracker tkr = MemTracker::get_realloc_tracker();
* ptr = ::realloc(...);
* if (ptr == NULL) {
* tkr.record(...)
* } else {
* tkr.discard();
* }
*
* MemTracker::Tracker tkr = MemTracker::get_virtual_memory_uncommit_tracker();
* if (uncommit(...)) {
* tkr.record(...);
* } else {
* tkr.discard();
* }
*
* MemTracker::Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
* if (release(...)) {
* tkr.record(...);
* } else {
* tkr.discard();
* }
*
* Since pre-reserved sequence number is only good for the generation that it is acquired,
* when there is pending Tracker that reserved sequence number, NMT sync-point has
* to be skipped to prevent from advancing generation. This is done by inc and dec
* MemTracker::_pending_op_count, when MemTracker::_pending_op_count > 0, NMT sync-point is skipped.
* Not all pre-reservation of sequence number will increment pending op count. For JavaThreads
* that honor safepoints, safepoint can not occur during the memory operations, so the
* pre-reserved sequence number won't cross the generation boundry.
*/
MemTracker::Tracker::Tracker(MemoryOperation op, Thread* thr) {
_op = NoOp;
_seq = 0;
if (MemTracker::is_on()) {
_java_thread = NULL;
_op = op;
// figure out if ThreadCritical lock is needed to write this operation
// to MemTracker
if (MemTracker::is_single_threaded_bootstrap()) {
thr = NULL;
} else if (thr == NULL) {
// don't use Thread::current(), since it is possible that
// the calling thread has yet to attach to VM 'Thread',
// which will result assertion failure
thr = ThreadLocalStorage::thread();
}
if (thr != NULL) {
// Check NMT load
MemTracker::check_NMT_load(thr);
if (thr->is_Java_thread() && ((JavaThread*)thr)->is_safepoint_visible()) {
_java_thread = (JavaThread*)thr;
JavaThreadState state = _java_thread->thread_state();
// JavaThreads that are safepoint safe, can run through safepoint,
// so ThreadCritical is needed to ensure no threads at safepoint create
// new records while the records are being gathered and the sequence number is changing
_need_thread_critical_lock =
SafepointSynchronize::safepoint_safe(_java_thread, state);
} else {
_need_thread_critical_lock = true;
}
} else {
_need_thread_critical_lock
= !MemTracker::is_single_threaded_bootstrap();
}
// see if we need to pre-reserve sequence number for this operation
if (_op == Realloc || _op == Uncommit || _op == Release) {
if (_need_thread_critical_lock) {
ThreadCritical tc;
MemTracker::inc_pending_op_count();
_seq = SequenceGenerator::next();
} else {
// for the threads that honor safepoints, no safepoint can occur
// during the lifespan of tracker, so we don't need to increase
// pending op count.
_seq = SequenceGenerator::next();
}
}
}
}
void MemTracker::Tracker::discard() {
if (MemTracker::is_on() && _seq != 0) {
if (_need_thread_critical_lock) {
ThreadCritical tc;
MemTracker::dec_pending_op_count();
}
_seq = 0;
}
}
void MemTracker::Tracker::record(address old_addr, address new_addr, size_t size,
MEMFLAGS flags, address pc) {
assert(old_addr != NULL && new_addr != NULL, "Sanity check");
assert(_op == Realloc || _op == NoOp, "Wrong call");
if (MemTracker::is_on() && NMT_CAN_TRACK(flags) && _op != NoOp) {
assert(_seq > 0, "Need pre-reserve sequence number");
if (_need_thread_critical_lock) {
ThreadCritical tc;
// free old address, use pre-reserved sequence number
MemTracker::write_tracking_record(old_addr, MemPointerRecord::free_tag(),
0, _seq, pc, _java_thread);
MemTracker::write_tracking_record(new_addr, flags | MemPointerRecord::malloc_tag(),
size, SequenceGenerator::next(), pc, _java_thread);
// decrement MemTracker pending_op_count
MemTracker::dec_pending_op_count();
} else {
// free old address, use pre-reserved sequence number
MemTracker::write_tracking_record(old_addr, MemPointerRecord::free_tag(),
0, _seq, pc, _java_thread);
MemTracker::write_tracking_record(new_addr, flags | MemPointerRecord::malloc_tag(),
size, SequenceGenerator::next(), pc, _java_thread);
}
_seq = 0;
}
}
void MemTracker::Tracker::record(address addr, size_t size, MEMFLAGS flags, address pc) {
// OOM already?
if (addr == NULL) return;
if (MemTracker::is_on() && NMT_CAN_TRACK(flags) && _op != NoOp) {
bool pre_reserved_seq = (_seq != 0);
address pc = CALLER_CALLER_PC;
MEMFLAGS orig_flags = flags;
// or the tagging flags
switch(_op) {
case Malloc:
flags |= MemPointerRecord::malloc_tag();
break;
case Free:
flags = MemPointerRecord::free_tag();
break;
case Realloc:
fatal("Use the other Tracker::record()");
break;
case Reserve:
case ReserveAndCommit:
flags |= MemPointerRecord::virtual_memory_reserve_tag();
break;
case Commit:
flags = MemPointerRecord::virtual_memory_commit_tag();
break;
case Type:
flags |= MemPointerRecord::virtual_memory_type_tag();
break;
case Uncommit:
assert(pre_reserved_seq, "Need pre-reserve sequence number");
flags = MemPointerRecord::virtual_memory_uncommit_tag();
break;
case Release:
assert(pre_reserved_seq, "Need pre-reserve sequence number");
flags = MemPointerRecord::virtual_memory_release_tag();
break;
case ArenaSize:
// a bit of hack here, add a small postive offset to arena
// address for its size record, so the size record is sorted
// right after arena record.
flags = MemPointerRecord::arena_size_tag();
addr += sizeof(void*);
break;
case StackRelease:
flags = MemPointerRecord::virtual_memory_release_tag();
break;
default:
ShouldNotReachHere();
}
// write memory tracking record
if (_need_thread_critical_lock) {
ThreadCritical tc;
if (_seq == 0) _seq = SequenceGenerator::next();
MemTracker::write_tracking_record(addr, flags, size, _seq, pc, _java_thread);
if (_op == ReserveAndCommit) {
MemTracker::write_tracking_record(addr, orig_flags | MemPointerRecord::virtual_memory_commit_tag(),
size, SequenceGenerator::next(), pc, _java_thread);
}
if (pre_reserved_seq) MemTracker::dec_pending_op_count();
} else {
if (_seq == 0) _seq = SequenceGenerator::next();
MemTracker::write_tracking_record(addr, flags, size, _seq, pc, _java_thread);
if (_op == ReserveAndCommit) {
MemTracker::write_tracking_record(addr, orig_flags | MemPointerRecord::virtual_memory_commit_tag(),
size, SequenceGenerator::next(), pc, _java_thread);
}
}
_seq = 0;
}
}
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